1.A book containing the words of a language, arranged alphabetically, with explanations of their meanings; a lexicon; a vocabulary; a wordbook.
[1913 Webster]I applied myself to the perusal of our writers; and noting whatever might be of use to ascertain or illustrate any word or phrase, accumulated in time the materials of a dictionary. --Johnson.[1913 Webster]

2.Hence, a book containing the words belonging to any system or province of knowledge, arranged alphabetically; as, a dictionary of medicine or of botany; a biographical dictionary.
[1913 Webster]. dictionary n : a reference book containing an alphabetical list of words with information about them [syn: {lexicon}].